4-Aminothiazole is an intermediate long sought in medicinal chemistry but hitherto unavailable because of the lack of operant procedures and because of the lability of 4-aminothiazole itself as well as possible intermediates for preparing it. 2-Aminothiazole is a well known and widely used intermediate. It is relatively stable as well as easy to use and prepare. The 2-isomer of the art is stable because of resonant forms possible with the 2-amino form. At the 4-position these resonant forms do not stabilize the ring making the 4-aminothiazole nucleus more susceptible to hydrolysis with the formation of unknown water soluble products.
4-Aminothiazole was mentioned in a physiochemical study of the thiazole ring but this publication refers to no method of preparation (Bull. Soc. Chim. Fr. 1967 3283-3293 C.A. 68 44384 m). In fact, examination of this paper reveals that the only data published on the compound are those theoretically observed but not actually measured using the compound itself. Therefore there is a strong inference that the compound was not in hand for this study.
In 1973, 4-aminothiazole was erroneously indexed by Chemical Abstracts (79, 32088g). The parent reference does not mention the compound. Various derivatives of 4-aminothiazole having stabilizing nuclear substitution have been reported especially the 2-bromo derivatives (U.S. Pat. No. 3,244,723) but to the best of our knowledge, 4 -aminothiazole itself has not been reported to be isolated in a form useful for synthetic purposes.